You're taking the wrong path, I see some things that you may not be considering.
Friendships don't need to be defined by beginnings and ends. The gentlest way to cool a friendship is to spend less time with them.
Spending time within someone you find attractive doesn't screw with your psyche. An internal cycle of hope and rejection does.
She already rejected you, you said it in the post. 'Its not the right time' is not an invitation to wait, it's a gentle no (and it's much worse approach than just saying no). Accept it and move on. If your thoughts wander to oh but maybe we could be together if I do something - remind yourself she said no. If you need further clarification ask again.
Threatening to end the friendship for a romantic relationship has zero good outcomes. If you can't handle the rejection or don't want to be her friend, then stop making time to see her. The only reason to explain that it is 'because you want more', is the thought that it will change her mind - remember emotional manipulation is gross and rapey but don't worry you haven't done it yet. Thinking about things isn't doing them.
Also, you sound like a young man, so I just want to affirm that the drive to have sex can be wild strong, and make clear thinking hard. It's okay, just remember you don't want be with someone who you can get to agree to a relationship with you, you want to be with someone who wants to be in a relationship with you. Everyone is worth that much.